Carburetor



G. GRIFFON Aug. 18, 1953 CARBURETOR Original Filed Feb. 15, 1947 ess. ama/azr 5 NEYS GfqsTo/v GRM-FON Patented Aug. 18, 1,953

CARBURETOR Gaston Griffon, Neuilly-sur-Seine, France, as-

signor to Societe Solex, a society of France `Continuation of abandonedapplication Serial No.

728,737, February 15, 1947. February 14, 1951, Serial No.

This application 210,824. In

France February 15, 1946 (Cl. Z61-34) 4 Claims.

The invention relates to carburetors for internal combustion engines andmore especially engines having a small number of cylinders.

Automatic carburetors, as now in use, permit of obtaining, when theengine is running on full load, a mixture the richness of which issubstantially constant for considerable flow rate variations, providedthat these carburetors are subjected to a continuous suction eiiect, asthis is the case for tests performed with a centrifugal fan forinstance, or when the carburetor is used in connection with an engineincluding more than four cylinders.

On the contrary, when these same carburetors are used with enginesrunning at high speeds and having a small number of cylinders (from oneto four) or on engines having six or four cylinders fed through a duplexcarburetor, the richness of the air-fuel mixture is greater at low andmean speeds than at high speeds of the engine.

The object of my invention is to obviate this drawback. For thispurpose, I combine a carburetor such as above mentioned with a pick-uppump controlling iuel delivery valve means such that the richness of themixture delivered when the engine is running with the throttle fullyopen remains substantially constant at all speeds, despite the smallnumber of cylinders of the engine.

Preferred embodiments of my invention will be hereinafter described Withreference to the accompanying drawings, given merely by way of exampleand in which: Y

Fig. l shows curves illustrating the object of my invention;Y

Fig. 2 shows, in axial section, a carburetor system made according to anembodiment of my invention; Y

Fig. 3 shows, in axial section, a modification of a part of thiscarburetor system;

Fig. li shows, in axial section, a modication of the rst embodiment. Y Y

Fig. l shows a series of curves intended to explain the operation oi thedevice according to my invention.

rEhe upper part of Fig. 1 shows several curves corresponding to therichness of the mixture supplied by a conventional automatic carburetorunder full load running conditions (with the throttle fully open) and atdifferent speeds of the engine, for instance from 1000 to 4000revolutions per minute, whereas the lower part of Fig. 1 shows thecorresponding specic consumption curves.

Curve A was obtained by fitting a good carburetor of a conventional typeon the induction pipe of a centrifugal fan. It shows that the richnessof the mixture for air flow rates corresponding to those obtained in anengine for speeds ranging from 1000 to 4000 revolutions per minute issubstantially constant for all the points of curve A.

Curve B-B was obtained with the same carburetor and the same adjustmentbut used in connection with a four cylinder engine. It will be seen thatthe richness oi the mixture is generally too high, being maximum forspeeds ranging from 1000 to i500 revolutions per minute, decreasing asthe engine speed increases up to 3200 revolutions per minuteapproximately (point B3), and then remaining substantially constant asthe engine speed increases up to the highest values. Curve C-C indicatesthe specific consumptions corresponding to curve B-B.

Curve B1-B3-B shows the results obtained when the system according to myinvention is used and curve C1-C gives the specific consumptionscorresponding to curve B1-B3-B.

Curve B1-B3-B2 shows what can be obtained with a modication of myinvention which maires it possible first to change curve B-B3 into curveBl-Ba, then, for speeds ranging up from 3500 revolutions per minute, toenrich the mixture in the manner indicated for instance by curve B3-B2-The corresponding curve of specific consumptions is shown at C1-C2.

To obtain such results, according to my invention, I combine anautomatic carburetor of a conventional type with a pick-up pump in amanner which will be hereinafter described. The essential parts of theconventional carburetor are visible on Fig. 2, to wit body I choke orventuri 2, calibrated jet 3 provided in the conduit ffl which connectsthe constant level chamber 2i' with nozzle device 5. The latter includesat its upper part a calibrated oriiice t for the iniiow of emulsion air.A throttle valve l is provided in the induction pipe 8 of the engine.

With such a carburetor used alone5 the richness curve under full loadrunning conditions and for speeds of the engine ranging from 1000 toi050 revolutions per minute would be similar to curve B--Bfi-B of Fig,l, and the corresponding speciflc consumption curve would be similar toC-C.

In order to improve this operation, I maire use of a pick-up pump tocontrol means for varying the section of a calibrated oriiice whichserves to deliver fuel, this calibrated oriice being either the main jetor an auxiliary jet.

In the example of Fig. 2, I make use of an auxiliary jet.

This auxiliary jet is constituted by a calibrated oriiice 4'! providedin a conduit d@ which opens into choke 2 through a calibrated orice 45.Conduit l186 starts from the suction pump, which is constituted by acasing divided into two iiuidtight chambers or compartments it and t9separated by a diaphragm 5t.

Compartment 43, which communicates with conduit 46, is fed with fuelthrough a connection 53 branching oi from the conduit t which connectsthe constant level chamber 2l with the main jet 3. A check Valve 58 inthis conduit 53 prevents back ow of fuel therethrough. Coinpartment t9communicates, through a tube with a chamber 55 adjacent to the inductionpipe 8 of the carburetor and which communicates with the inside thereofboth on the upstream side of throttle valve 'through an oriiice 5d, andon the downstream side thereof through an orifice 51.

A check valve 59 in the pump delivery conduit i6 prevents bach flow ofair into the during the suction stroke of said pump.

Diaphragm 5d carries a central needle valve 5i capable of more or lessobturating auxiliary jet fil. Diaphragm t@ is urged, on the face thereofopposed to that which car 1ics needle val"e by a spring 552 bearing uponthe end wall of compartment d@ and which tends to apply needle valve 5ion its seat constituted by the edge of orifice 4l.

The carburetor is adjusted through the usual means, that is to say by asuitable choice of jet and emulsion air orifice t, to obtain, when theengine is running with the throttle iiaiiy open and at a speed of about1500 revolutio s per m the desired value of the fuel in (point Bi of thecurve of Fig. l).

The operation is as follows.

openings of throttie l, the suction. is very iiign in the inductionconduit E of the engine and, consequently, opposite orifice El', whereasit is very low opposite orifice 5t. Therefore, in chiii and tube thereis a vacuum between the suctions on the upstream and sownstream sides orthrottle valve l, w h vs transmitted to compartment il@ of the piek-uppump.

The sections of orices 5S and il are determined in such manner that,when the engine is idling or throttle valve l little open-e the effortexerted upon diaphragm created in compartment de overcomes the action ofspring 52 and therefore causes diaphragm ilfi to move toward the rightof Fig. 7. This displacement causes, on the one hand, fuel to fiow intocompartment and, on the other hand, needle valve 5i to move away fromjet and therefore to clear the passage through this jet.

Now if the engine is made to pick up, that is to say if, starting from alow speed of said engine, throttle l' is suddenly opened, the highvacuum which existed opposite orifice 5l drops to a low value. Thevacuum accordingly drops in coinpartinent fifi. Diaphragm liti movestoward the left and causes a certain amount of fuel to be deliveredthrough conduit fit.

At the end of the pick-up pump delivery stroke, needle valve 5i restsupon its seat, preventing the fiow of fuel through jet fil. Thisposition of the needle valve corresponds to low speed running of theengine, with throttle 'i fully open. rlhese are the conditions forwhich, as above stated, the carburetor has been adjusted to have a fuelrichness represented by the point B1 oi the curves of Fig. l. Ii thecarburetor were used alone, i. e. without the pick-up pump and the meansit conby the partial vacuum trols, the richness of the mixture wouldtend to decrease for increasing values of the engine speed, as shown inthe portion B-Ba of the curve B-Ba-B of Fig. 1.

But, as the engine speed increases, the suction increases oppositeorifices tit and 5? so that the vacuum in compartment i9 reaches a valuesufficient for again causing diaphragm 5e to move to- Vward the rightagainst the action of spring whereby needle valve 5i again ciears thepassage through auxiliary jet fil, the rate of iiow th sugli saidauxiliary jet increasing according to a predetermined law as the speedor" the engine increases, to reach its maximum either for a speedcorresponding to about 3200 revolutions per ii inute if it is desired tokeep a substantially constant richness, as in the case of curve Bi-Bs-B,or for a iglier speed if it is desired to obtain a richer mixture at thehighest speeds of the engine, an arrangement which gives a richnesscurve analogous to Bi-B3-B2 of Fig. l for instance.

The strength of spring 52 determines the time at which diaphragm 5tstarts moving toward 'he right of fig` 2 and its i'ie; ty determines hrange of displacement of needle valve El. profile of said valve '5i ietes the richness of the mixture for every speed the engine inside therange for which the correcting device is brought into play.

It may be advantageous, in some cases, in addition to the eifects abovedescribed, to reduce the richness of the mixture for lower powerrunning. This result can be obtained by placing orifice 5l nearer to thethrottle, at ci! for instance, whereby said orifice passes from theupstream to the downstream side for a certain degree of opening ofthrottle l.

I may also, as shown by Fig. 3, move, by means of diaphragm 50, a needlevalve 5i provided with a check valve 5 I located on the side ofcalibrated orifice 4'! opposed to said needle valve 5! so that saidcheck valve can close said oriiice at the end of movement of diaphragm5t toward the right.

Chamber 49 is then placed in communication either with orices 56 and 5las in Fig. 2, or with only orifice 5l that is located on the downstreamside of throttle 'I when it is desired to obtain a quick closing oforifice il and therefore a reduction of the richness of the mixture forpowers close to the maximum power.

The working is the same as that of Fig. 2 concerning full throttlerunning, which means that under full load running conditions, at lowspeeds of the engine, diaphragm 5! is pushed toward the left by spring52 and, consequently, needle valve 5l closes passage 4l. For higherspeeds, needle valve 5l gradually clears passage i? whereas check valve5l' moves closer and closer thereto, but without stopping it. For partlyclosed throttle running, the suction in the pipes reaches values higherthan those obtained at high speed and under full load runningconditions. Diaphragm 50 therefore keeps moving toward the right andpassage 41 gets closed by check valve 5|. This closing may be eithergradual or sudden according to the shape given to check valve 5 l InFig. 4 I have shown a modification of the device of Fig. 2 according towhich a needle valve 6I controls the ow section through the single mainjet 3. This needle valve is controlled through pneumatic means as abovedescribed, adapted to work also as pick-up pump. It sufces, for thispurpose, to provide a check valve S2 in conduit 4, which leads fromchamber 21 to the main jet. The injection of fuel during picking-upperiods then takes place directly into nozzle device 5.

The present application is a continuation of my application Ser. No.728,737, filed February 15, 1947, now abandoned.

In a general manner, while I have, in the above description, disclosedWhat I deem to be practical and eflicient embodiments of my invention,it should be well understood that I do not wish to be limited thereto asthere might be changes made in the arrangement, disposition and form ofthe parts without departing from the principle of the present inventionas comprehended Within the scope of the accompanying claims.

What I claim is:

1. For use in connection with an internal combustion engine, thecombination of a carburetor including an induction pipe and a throttlein said pipe, an automatic pick-up pump operative in response tovariations of the suction in said pipe on both sides of said throttle,this pump including a part movable in response to variations of thissuction from one position corresponding to the minimum value of thissuction to another position corresponding to the maximum value of saidsuction, and a fuel discharge conduit leading from said pump to saidpipe, and a metering valve operatively connected with said movable partand located in said fuel discharge conduit, said valve being so shapedand connected with said movable part as to increase gradually the flowsection through said conduit in response to displacement of said movablepart from said rst mentioned position thereof to said second one.

2. For use in connection with internal combustion engine, thecombination of a carburetor including an induction pipe, a throttle insaid pipe and a fuel conduit opening into said pipe, an automaticpick-up pump operative in response to variations of the suction in saidpipe on both sides of said throttle, this pump including a fuel chamberhaving a Wall movable in response to variations of this suction from oneposition corresponding to a minimum value 4of this suction to anotherposition corresponding to a maximum value of said suction, asupplementary fuel discharge conduit leading to said induction pipe, theoutlet of said pump opening into said supplementary fuel conduit, and ametering valve operatively connected with said movable wall and locatedin said supplementary fuel discharge conduit, said valve being so shapedand connected with said movable part as to increase gradually the flowsection through said supplementary conduit in response to displacementof said movable part from said first mentioned position thereof to saidsecond one.

3. A combination according to claim 2 further including a check valvecarried by said valve means to stop the flow of said supplementaryconduit when said movable wall is at the end of its displacementproduced by increasing suction on the downstream side of said throttle.

4. For use in connection with an internal combustion engine, thecombination of a carburetor including an induction pipe, a throttle insaid pipe and .a single fuel conduit opening into said pipe, anautomatic pick-up pump operative in response to variations of thesuction in said pipe on both sides of said throttle, the outlet of saidpump opening into said conduit, this pump including a fuel chamberhaving a wall movable in response to variations of this suction from oneposition corresponding to a minimum value of this suction to anotherposition corresponding to a maximum value of said suction, and ametering valve operatively connected with said movable wall and locatedin said outlet, said valve being so shaped and connected With saidmovable part as to increase gradually the ow section through said outletin response to displacement of said movable part from said firstmentioned position thereof to said second one.

GASTON GRIFFON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,389,922 Mennesson Nov. 27, 1945 2,392,055 Mennesson Jan. 1,1946 2,563,096 Bicknell Aug. 7, 1951 2,572,169 Mallory Oct. 23, 1951

